The present invention relates to manually controlled static switches, i.e. any device making it possible to supply at at least one output terminal a signal able to assume at least two levels, one of the two levels being obtained on e.g. manually applying an element to a given location. It also applies to the application of these switches to the sequential control of elements, e.g. electronic elements, as a function of a given position of a preferably manually displaceable element.
Switches of the aforementioned type already exist, which can be manually controlled. They are generally provided, beneath a flexible wall, with two facing contacts subject to the action of recoil spring means, e.g. made from a material which does not conduct electricity. In order to control such a switch, it is merely necessary, e.g. through the direct or indirect action of a finger, to exercise a slight pressure on the flexible wall in order to bring into contact the two contacts, which then establish the switching function, e.g. for closing a circuit. Although this system gives good results, it still requires use precautions, because excessive pressure forces could lead to the more or less rapid destruction of the contacts, particularly in special applications, such as e.g. the control of different musical elements in theatres, concert halls and the like, where the means are often subject to rough handling.
There are also other completely static switches, which generally comprise an electromagnetic wave beam source with a cell for receiving the beams located at a certain distance from the source, so as to permit the passage between them of an element, such as e.g. the finger of a hand.
These devices adequately fulfil the functions required. However, in the case of an application such as to a control potentiometer in an audio mixer, they may suffer from two disadvantages. Firstly the user does not have the touch sensation, which is necessary e.g. in the case referred to hereinbefore and secondly he does not know at precisely which point he has placed his finger.